The present invention relates to an anchoring plug assembly used for fastening an object to a supporting structure. More particularly, the invention relates to an anchoring assembly for anchoring in drilled holes having widening undercut portions.
An anchoring plug assembly or an expansion dowel of the type under discussion comprises a slotted expansion sleeve and an expander cone which is movable in the axial direction of the sleeve by a bolt to anchor the plug in the hole provided in the supporting structure, for example, masonry.
Anchoring plugs of the foregoing type have been disclosed, for example, in applicant's U.S. Pat. Nos. 3,277,623; 3,082,657; 3,524,379; 3,815,467; 4,094,054; 4,094,223; 4,182,091; 4,065,996; 4,050,346; 4,516,378, etc. When using bored holes which are widened at their leading ends it is possible to achieve anchorages which are virtually free from expansion pressures and which additionally produce even higher holding values owing to the increased expansion of the fixing element which is the aforementioned bolt. Known expansible anchoring plugs have an expander cone onto which an expansible sleeve can be driven by a suitable driving-in tool. The expander cone can be formed on a further bolt which is joined by a screw connection to the threaded bolt. The threaded bolt projects with its external end from the drilled hole and may have an external thread so that an article to be anchored to the supporting structure can be screwed tightly to the external wall of this structure, such as masonry or a ceiling, by means of a nut.
Known expansible anchoring plugs which can be inserted by being driven into a bored hole having a frustoconical undercut require special driving-in tools and are not readily adaptable to different clamping lengths of the articles to be anchored to masonry or ceilings.